Cash back not being paid

I have received and sms on the 13 August 2020 from Old Mutual saying I have cash back from 2 of my policies that I have with them, and I will receive the cash on my account within 2 days, which I didn’t receive anything till today, call their useless call center didn’t get response, i sent them 20 emails only thing I get is that stupid automatic email response, I went to Randburg office they are telling me they don’t see that cash back money where is been deposited, to my surprise one email said they couldn’t deposit money to my account I should send proof of my banking details which I didn’t , what makes me angry is that is easy for them to debit their premium on my account every single month but when the need to deposit money in to my account it’s hard